Giant switchable ferroelectric photovoltage in double-perovskite epitaxial films through chemical negative strain.

Tu, Jie; Li, Hangren; Liu, Xudong; Xi, Guoqiang; Liu, Xiuqiao; Zhang, Mengqi; Wu, Rong; Du, Siyuan et al. · Sci Adv · 2025

basic_science · Level V

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Abstract

Double-perovskite films have been extensively studied in multifunctional fields due to their modifiability. Here, a controlled process strategy to induce chemical strain and anomalous Poisson deformation is proposed for perovskite-based films. The chemical negative strain in the local-ordering BiSmFe<sub>2</sub>O<sub>6</sub> double-perovskite films can be regulated by oxygen engineering to cause the effectively tunable bandgap. We markedly increased the switchable open-circuit voltage to ~1.56 V from ~0.50 V for Pt/BiSmFe<sub>2</sub>O<sub>6</sub>/Nb-SrTiO<sub>3</sub> devices, which is the highest in single-layer perovskite-based ferroelectric photovoltaic perpendicular devices under white light-emitting diode irradiation. The multifield composite action mechanism reveals the electrical cause of the large open-circuit voltage. The synergy of the optical fields and ferroelectric fields provides the possibility of multilevel storage. Structural characterizations indicate that the chemical strain offers a dual role of lattice distortion and vacancy migration. The strategy of controllable chemical strain facilitates further exploration of the application potential of ferroelectric materials for multifunctional electronic devices.